As recently as two years ago there were few microarray technologies available. In the last year, in both industrial and academic settings, new methodologies for fabricating microarrays and novel detection systems have been developed. The technologies that are currently available through commercial ventures are very expensive. The actual cost of these technologies is beyond the reach of small university-based research laboratory budgets. Furthermore, the needs of the university-based researchers are usually quite specific and dictate the need for custom arrays that are not commercially available. The challenge that faces this group of NCI-funded researchers is how to take advantage of these technologies within the constraints of R01 budgets. Our goal is to be able to build microarrays that are of high density enabling us to simultaneously measure the expression of a major portion of the genome at one time. The Program Announcement sponsored by the NCI entitled "Shared Resources for Scientists Outside NCI Cancer Centers" affords us the opportunity to address array fabrication and enhance array detection to be more flexible. Our goal is to build a shared resource core dedicated to making and using DNA microarrays for a better understanding of the genes involved in tumorigenesis. In particular, we would like this core to have the ability to make custom arrays, a capacity that is imperative to remain competitive. With the custom "in-house" facility, we can pursue microarray assays not commercially available and at a much lower cost. Microarrays of this sort make sense for many applications within our laboratories including gene expression, genotyping, re-sequencing and mutation screening assays.